This invention concerns a knee brace for controlling ligament instability, and more particularly to a knee brace havinq upper and lower cuffs joined by a polycentric hinqe on the lateral side of the brace and a pivotal articulation plate at the medial side of the brace.
When the liqaments surrounding the knee have been traumatized by injury or by surgery, a supporting brace is used to provide stability while still allowinq movement of the knee. The brace should provide stability when forces are applied to the knee in the medial and lateral (side) planes and in the anterior (front) and posterior (rear) planes. In addition, the brace should provide rotational stability so as to prevent excessive axial rotation of the tibia with respect to the femur. The brace should also prevent forward movement of the tibia with respect to the femur, a function provided in the normal knee by the anterior cruciate ligament.
A knee brace for control of ligament instability is described in U.S. Pat. No. 4,633,867 to Kausek et al. That brace includes a thigh cuff, a shin plate, and a rear calf cuff. In that brace two polycentric hinges are provided at the medial and lateral sides of the brace. While use of polycentric hinges on both sides of the knee provides good ligament control. The movement of the knee is somewhat restricted.
Knee braces havinq a lateral hinqe, but no medial hinqe, are often worn by football players to prevent injury. They may also be used for rehabilitation or to support a knee which exhibits chronic instability. The lateral hinqe, which may be monocentric or polycentric, has upper and lower lateral plates which are either taped to the leg or inserted in a wrap-around neoprene sleeve by Velcro straps with closures. This brace provides greater support when taped to the leg, but taping is uncomfortable and not practical for daily use. The brace provides less support when attached via the neoprene sleeve.
It would thus be desirable to provide a knee brace which provides good ligament control while allowing a natural ranqe of movement of the knee, and which is comfortable to wear and easily removable for daily use It is also desirable to provide a brace which offers some adjustability as to size and thus can be sold as an of-the-shelf item. These and other features are provided by the knee brace of the present invention.